Op-Amp Fuse Adjustment Circuit for Reliable Offset Trimming

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Solution Overview

Problem

Existing operational amplifiers face challenges in accurately adjusting input offset voltage due to unreliable disconnection of fuses, which can lead to inconsistent circuit performance.

Innovation Solution

The operational amplifier incorporates a current adjustment circuit with a sink circuit and a control circuit, utilizing a series connection of fuses in adjustment paths to ensure reliable disconnection and precise adjustment of current paths, thereby controlling the input offset voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single fuse is used for adjusting input offset voltage, then the adjustment function can be achieved, but the disconnection reliability is insufficient leading to inconsistent circuit performance

Engineering Contradiction:
Improvedisconnection reliabilityVSAvoidadjustment circuit complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The adjustment circuit is divided into multiple independent adjustment paths (first adjustment path with first fuse, second adjustment path with second fuse). Each path can independently control different aspects of the input offset voltage, allowing the system to achieve reliable adjustment even if one path fails to disconnect properly.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If multiple adjustment paths are added to improve adjustment precision, then the input offset voltage control is enhanced, but the circuit complexity increases

Engineering Contradiction:
Improveinput offset voltage adjustment precisionVSAvoidadjustment circuit complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The adjustment circuit is divided into multiple independent adjustment paths (first adjustment path with first fuse, second adjustment path with second fuse). Each path can independently control different aspects of the input offset voltage, allowing the system to achieve reliable adjustment even if one path fails to disconnect properly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent provides more adjustment paths than strictly necessary (excessive action), ensuring that even if some paths fail to disconnect, the remaining paths can still achieve the required adjustment precision. This redundancy prioritizes adjustment reliability over minimal circuit complexity.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentUS20250293649A1Adjustment circuit and adjustment method using the same, current adjustment circuit and current adjustment method using the same, operational amplifier, and offset adjustment method
Publication Date: 2025.09.18 ROHM CO LTD
  • US20250293649A1 patent drawing
  • US20250293649A1 patent drawing
  • US20250293649A1 patent drawing

AI summary

An adjustment circuit is disposed between a first node and a second node. The adjustment circuit comprises a plurality of disconnection target elements connected in series and is configured such that the first node and the second node are electrically connected via the adjustment circuit when none of the plurality of disconnection target elements are disconnected, and the adjustment circuit is open as viewed from the first node when at least one of the plurality of disconnection target elements is disconnected.